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    <font size="7">Filesystem
    Version 3<br>
    Introduction</font></td>
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<h1>Boost Filesystem Version 3</h1>

<p>Version 3 is a major revision of the Boost Filesystem library. Important
changes include:</p>

<ul>
  <li>A single class <code>path</code> handles all aspects of
  internationalization, replacing the previous template and its <code>path</code>
  and <code>wpath</code> instantiations. Character types <code>char</code>,
  <code>wchar_t</code>, <code>char16_t</code>, and <code>char32_t</code> are
  supported. This is a major simplification of the path abstraction,
  particularly for functions that take path arguments.<br>
&nbsp;</li>
  <li>New <code>class path</code> members include:<br>
&nbsp;<ul>
  <li><code><a href="reference.html#path-has_stem">has_stem</a>()</code></li>
  <li><code><a href="reference.html#path-has_extension">has_extension</a>()</code></li>
  <li><code><a href="reference.html#path-is_absolute">is_absolute</a>()</code>. This renames <code>is_complete()</code>, which
  is now deprecated.</li>
  <li><code><a href="reference.html#path-is_relative">is_relative</a>()</code></li>
  <li><code><a href="reference.html#path-make_preferred">make_preferred</a>()<br>
&nbsp;</code></li>
</ul>

  </li>
  <li>New or improved operations functions include:<br>
&nbsp;<ul>
    <li><code><a href="reference.html#absolute">absolute</a>()</code>. This replaces the operations function <code>
  complete()</code>, which is now deprecated. Semantics are now provided for a
    Windows corner case where the <code>base</code> argument was not an absolute
    path. Previously this resulted in an exception being thrown.</li>
    <li><code><a href="reference.html#create_symlink">create_symlink</a>()</code> now supported on both POSIX and Windows.</li>
    <li><code><a href="reference.html#read_symlink">read_symlink</a>()</code> function added. Supported on both POSIX and
    Windows. Used to read the contents of a symlink itself.</li>
    <li><code><a href="reference.html#resize_file">resize_file</a>()</code> function added. Supported on both POSIX and
    Windows. Used to shrink or grow a regular file.</li>
    <li><code><a href="reference.html#unique_path">unique_path</a>()</code> function added. Supported on both POSIX and
    Windows. Used to generate a secure temporary pathname.<br>
&nbsp;</li>
  </ul>
  </li>
  <li>Support for error reporting via <code>error_code</code> is now uniform
  throughout the operations functions.<br>
&nbsp;</li>
  <li>Documentation has been reworked, including re-writes of major portions.<br>
&nbsp;</li>
  <li>A new <a href="tutorial.html">Tutorial</a> provides a hopefully much
  gentler and more complete introduction for new users. Current users might want
  to review the <a href="tutorial.html">three sections related to class path</a>.</li>
</ul>

<h2>Deprecated names and other features</h2>

<p>See the <a href="deprecated.html">Deprecated Features page</a> for transition
aids that allow much existing code to compile without change using Version 3.</p>

<h2>Breaking changes</h2>

<p>To ease the transition, Versions 2 and 3 both used to be included in the next
several Boost releases. Version 2 was removed in Boost 1.50.0.</p>
<h3>Class <code>path</code></h3>
<ul>
  <li>Class template <code>basic_path</code> and its specializations are
  replaced by a single <code>class path</code>. Thus any code, such as
  overloaded functions, that depends on <code>path</code> and <code>wpath</code>
  being two distinct types will fail to compile and must be restructured.
  Restructuring may be as simple as removing one of the overloads, but also
  might require more complex redesign.<br>
&nbsp;</li>
  <li>Certain functions now return <code>path</code> objects rather than <code>
  string or wstring</code> objects:<ul>
    <li><code>root_name()</code></li>
    <li><code>root_directory()</code></li>
    <li><code>filename()</code></li>
    <li><code>stem()</code></li>
    <li><code>extension()</code></li>
  </ul>
  <p>Not all uses will fail; if the function is being called in a context that
  accepts a <code>path</code>, all is well. If the result is being used in a
  context requiring a <code>std::string</code> or <code>std::wstring</code>,
  then <code>.string()</code> or <code>.wstring()</code> respectively must be
  appended to the function call.<br>
&nbsp;</li>
  <li>&nbsp;<code>path::iterator::value_type</code> and&nbsp; <code>
  path::const_iterator::value_type</code> is <code>path</code> rather than <code>
  basic_string</code>.</li>
</ul>
<h3>Compiler support</h3>
<ul>
  <li>Compilers and standard libraries that do not fully support wide characters
  and wide character strings (<code>std::wstring</code>) are no longer
  supported.<br>
&nbsp;</li>
  <li>Cygwin versions prior to 1.7 are no longer supported because they lack
  wide string support. Cygwin now compiles only for the Windows API and path
  syntax.<br>
&nbsp;</li>
  <li>MinGW versions not supporting wide strings are no longer supported.<br>
&nbsp;</li>
  <li>Microsoft VC++ 7.1 and earlier are no longer supported.</li>
</ul>

<hr>
<p>&copy; Copyright Beman Dawes, 2009</p>
<p>Distributed under the Boost Software License, Version 1.0. See
<a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a></p>

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